RadGrid not firing postback on ItemCommand events

I'm currently evaluating some RAD controls from Telerik, just right now I'm experimenting with the RadGrid.

So I have my grid control and enabled client-side binding for having Ajax support. I created an appropriate WCF webservice for fetching the data etc. Everything works really good, including paging etc. Now I wanted to have a button column for deleting some items. I registered the OnItemCommand event of the grid and implemented it accordingly on the server-side. My ASPx code looks like this:

<telerik:RadGrid runat="server" ID="RadGrid1" AllowPaging="True" AllowSorting="True"
    AutoGenerateColumns="False" GridLines="None"
    OnItemCommand="RadGrid1_ItemCommand">
    <MasterTableView DataKeyNames="Id" ClientDataKeyNames="Id">
        <Columns>
            <telerik:GridBoundColumn DataField="Firstname" HeaderText="Firstname" DataType="System.String">
            </telerik:GridBoundColumn>
            <telerik:GridBoundColumn DataField="Lastname" HeaderText="Lastname" DataType="System.String">
            </telerik:GridBoundColumn>
            <telerik:GridBoundColumn DataField="Age" HeaderText="Age" DataType="System.Int32">
            </telerik:GridBoundColumn>
            <telerik:GridButtonColumn CommandName="Delete" Text="Delete" UniqueName="DeleteColumn"
                ButtonType="ImageButton">
            </telerik:GridButtonColumn>
        </Columns>
        <PagerStyle Mode="Slider" />
    </MasterTableView>
    <ClientSettings>
        <DataBinding SelectMethod="GetSampleData" Location="Webservice/GridData.svc" SortParameterType="String">
        </DataBinding>
    </ClientSettings>
</telerik:RadGrid>

However when clicking on the appropriate button on a grid row the event isn't fired, basically no postback to the server is being done. A solution I found is to add the "EnablePostBackOnRowClick=true" to the ClientSettings, but this would cause a postback on each click on a row, which is not really desired.

Is there a better way to realizing this or does anybody have a hint what could be the problem??

Thx

As far as it seems this is not possible given the answer from the Telerik forum.